Positioning arrangement for components of a pressure vessel and method

ABSTRACT

The positioning arrangement comprises at least one pair of complimentary rounded recesses, each recess being provided on the mating face of the corresponding component. One ball is positioned between each pair of complementary recesses.

TECHNICAL FIELD

The invention relates generally to a positioning arrangement forcomponents of a pressure vessel and to a method of positioning twoadjacent components of a pressure vessel.

BACKGROUND OF THE ART

Pressure vessels are often made of two or more components that areconnected together at some point during manufacturing. These componentsgenerally have mating faces that are provided with complementarypositioning elements to ensure that the components are perfectlyaligned. These positioning elements have a number of advantages,including being able to ensure that components are always oriented inaccordance with their design. However, pressure vessels, particularlythin wall pressure vessels, are often prone to high stress concentrationwhen provided with these positioning elements.

In some arrangements, the positioning elements include a cylindrical pinlocated at the interface between the two components being joinedtogether. Cylindrical pins have some limitations and drawbacks. Atfirst, small cylindrical pins are difficult to handle during theassembly and pins manufactured with very small tolerances are expensive.They can also be easily damaged if they are not handled properly. Then,the arrangements require that two perfectly colinear cylindrical holesbe provided in the adjacent surfaces. These holes produce stressconcentrations due to the relatively deep holes that are required andthe sharp edges thereof.

Accordingly, there is a need to provide an improved positioningarrangement for components of a pressure vessel, and a method ofassembling two adjacent components of a pressure vessel, with veryminimal stress concentrations.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide an improvedpositioning arrangement for a pressure vessel, and an improved method ofassembling two adjacent structures of a pressure vessel.

In one aspect, the present invention provides a positioning arrangementfor a pressure vessel having at least two adjacent components to besecured together at mating faces, the arrangement comprising: at leastone pair of complementary recesses forming a rounded space, each recessbeing provided on the mating face of one corresponding component; andone ball positioned in the rounded space of one corresponding pair ofcomplementary recesses.

In another aspect, the present invention provides a method of assemblingtwo adjacent components of a pressure vessel, the method comprising:machining a first recess in one of the components; machining a secondrecess in the other component, the two recesses being complementary andforming a rounded space when the two adjacent components are beingassembled; and providing a ball between the two complementary recesses,the ball having an external shape and size which are substantiallyidentical to an internal shape and size of the rounded space.

In another aspect, the present invention provides a pressure vesselarrangement having at least two adjacent components to be securedtogether at mating faces, one of the two components being a fuel nozzle,the arrangement comprising: at least one pair of complementary roundedrecesses forming a space, each recess being provided on the mating faceof one corresponding component, and one rounded element snugly fitted inthe space of one corresponding pair of complementary recesses.

Further details of these and other aspects of the present invention willbe apparent from the detailed description and figures included below.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying figures depicting aspects ofthe present invention, in which:

FIG. 1 schematically shows a generic gas turbine engine to illustrate anexample of a general environment in which the invention can be used.

FIG. 2 is a schematic side view showing an example of a pressure vesselwith two different positioning arrangements.

FIG. 3 is an enlarged schematic cross-section view of an example of apositioning arrangement in accordance with the present invention.

FIG. 4 is an enlarged schematic cross-section view of another example ofa positioning arrangement in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a gas turbine engine 10 of a type preferably providedfor use in subsonic flight, generally comprising in serial flowcommunication a fan 12 through which ambient air is propelled, amultistage compressor 14 for pressurizing the air, a combustor 16 inwhich the compressed air is mixed with fuel and ignited for generatingan annular stream of hot combustion gases, and a turbine section 18 forextracting energy from the combustion gases.

A pressure vessel can be generally defined as a hollow structure whichwill be pressurized at one point during its use. This pressure willgenerate internal forces in the material of the structure. Very often, apressure vessel is made of at least two components that are securedtogether using bolts, welds, solders or any other suitable kind offasteners. An example of such pressure vessels is the engine casing ofthe gas turbine engine 10.

FIG. 2 schematically illustrates an example of a pressure vessel 20having two mating components 22, 24 being secured together usingfasteners (not shown). In this case, the pressure vessel 20 comprisesthe walls of a fuel nozzle 100.

To ensure that the mating components 22, 24 of the pressure vessel 20are aligned relative to each other with a very high degree of accuracy,the present invention uses at least one rounded element, preferably aspherical ball 30, which is designed to fit between a pair of oppositecomplementary recesses 32, 34 machined in the mating faces of thecomponents 22, 24, which complementary recesses 32, 34 form together arounded space in which the ball 30 is set. FIG. 2 also illustrates, onthe left side, a pin 102 similar to the ones used in the prior art.

Preferably, as illustrated, the rounded space and the ball 30 arespherical. Moreover, more than one set of spherical balls 30 andcorresponding spherical recesses 32, 34 are preferably provided andtheir position is such that during assembly, the components 22, 24cannot be assembled with a wrong orientation. For instance, the positionof the various balls 30 can be out of alignment with reference to a lineof symmetry of the components 22, 24 for this purpose.

The advantages of using balls 30 and corresponding recesses 32, 34 arenumerous. First, the balls 30 are available at low cost with veryaccurate tolerances. They are available in a large number of sizes.Balls 30 can be easily manipulated with equipment devised for balltacking and they can be easily positioned during the manufacturing.These balls 30 are more robust than pins, especially during handling ordropping. Moreover, the rounded recesses 32, 34 in the arrangementproduce a far lower stress concentration in critical areas due to theirsmooth geometry. This is particularly advantageous in the case ofpressure vessels having a thin wall, in which conventional positioningarrangements cannot be used because they can introduce severe stressconcentrations.

If desired, the ball 30 can be partially embedded in a recess 34provided in one of the components, which recess 34 is located deeper inthe corresponding component 34 than the opposite recess 32 of theadjacent component 24. This second component 24 would have only itsrecess 34 shaped as a segment of the geometric form, as illustrated inFIG. 4. Both recesses 32, 34 are thus nonidentical. This is useful, forinstance, if one component is thinner than the other.

It should be noted that FIGS. 3 and 4 illustrate the components 22, 24,the recesses 32, 34 and the ball 30 having a very large tolerancebetween them. This is only for the purpose of better illustration. Infact, the outside shape and size of the ball 30 is substantiallyidentical to the interior shape and size of the space.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without departing from the scope of the invention disclosed.For example, the present invention is not limited to pressure vesselsused in a gas turbine engine. The ball 30 and the corresponding recesses32, 34 can have a rounded shape which is not necessarily spherical, suchas ovoid, ellipsoid, spheroid, conoid, etc. Still other modificationswhich fall within the scope of the present invention will be apparent tothose skilled in the art, in light of a review of this disclosure, andsuch modifications are intended to fall within the appended claims.

1. A positioning arrangement for a pressure vessel having at least twoadjacent components to be secured together at mating faces, thearrangement comprising: at least one pair of complementary recessesforming a rounded space, each recess being provided on the mating faceof one corresponding component, and one ball positioned in the roundedspace of one corresponding pair of complementary recesses.
 2. Thepositioning arrangement as defined in claim 1, wherein the rounded spaceand the corresponding ball are spherical.
 3. The positioning arrangementas defined in claim 1, wherein the pressure vessel comprises a fuelnozzle.
 4. The positioning arrangement as defined in claim 1, whereinthe recesses of a same pair are identical.
 5. The positioningarrangement as defined in claim 1, wherein the recesses of a same pairare nonidentical.
 6. A method of assembling two adjacent components of apressure vessel, the method comprising: machining a first recess in oneof the components; machining a second recess in the other component, thetwo recesses being complementary and forming a rounded space when thetwo adjacent components are being assembled; and providing a ballbetween the two complementary recesses, the ball having an externalshape and size which are substantially identical to an internal shapeand size of the rounded space.
 7. The method as defined in claim 6,wherein the rounded space and the corresponding ball are spherical. 8.The method as defined in claim 6, wherein the pressure vessel comprisesa fuel nozzle.
 9. The method as defined in claim 6, wherein the recessesof a same pair are identical.
 10. The method as defined in claim 6,wherein the recesses of a same pair are nonidentical.
 11. A pressurevessel arrangement having at least two adjacent components to be securedtogether at mating faces, one of the two components being a fuel nozzle,the arrangement comprising: at least one pair of complementary roundedrecesses forming a space, each recess being provided on the mating faceof one corresponding component, and one rounded element snugly fitted inthe space of one corresponding pair of complementary recesses.
 12. Thepositioning arrangement as defined in claim 11, wherein the roundedelement is a spherical ball.
 13. The positioning arrangement as definedin claim 11, wherein the recesses of a same pair are identical.
 14. Thepositioning arrangement as defined in claim 11, wherein the recesses ofa same pair are nonidentical.